T-Mobile myTouch Q BL-48LN Replacement Battery 3.7V 2400mAh

T-Mobile myTouch Q Series — 3.7V Li-ion Replacement Battery (BL-48LN)

This is a 3.7V, 2400mAh Li-ion replacement cell for the T-Mobile myTouch Q and myTouch Q 4G smartphones. It uses OEM part number BL-48LN and slots into the same battery compartment as the original. If your myTouch Q shuts down unexpectedly, won't hold a charge, or won't power on at all, this cell addresses those failures directly.

• myTouch Q and Q 4G compatibility: Both the myTouch Q and myTouch Q 4G share the same 3.7V single-cell architecture and BL-48LN connector pinout. The BMS handshake and thermistor line are identical across both variants, so one cell covers both devices without modification.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on the myTouch Q platform. The BMS held the charge termination voltage correctly and the protection circuit tripped at the expected cutoff floor — no anomalous heat or mid-cycle drops detected.
• Fuel gauge recalibration on first use: After installing this cell, run one complete discharge down to auto-shutdown, then charge uninterrupted to 100% before normal use. The myTouch Q's fuel gauge IC is calibrated to the old cell's discharge curve — one full cycle resets the coulomb counter against the new cell's actual capacity.

Sudden shutdown at 20–30% on the myTouch Q after a cell swap

The myTouch Q's fuel gauge IC tracks capacity using a coulomb counter that was calibrated against the original cell's internal resistance profile. A new cell has a different impedance curve, so the reported percentage drifts from actual cell voltage. Under modem or screen load, the real cell voltage drops below the safe floor before the OS expects it — triggering an abrupt shutdown at what the display shows as 20–30%. One full discharge-to-shutdown and uninterrupted recharge cycle forces the fuel gauge IC to resync its reference points to the new cell. After that cycle, shutdown behaviour should normalise.

myTouch Q won't power on after sitting in storage with a flat battery

If a Li-ion cell drops below approximately 2.5V during extended storage, the BMS enters a protection lockout state and blocks normal charging current. The myTouch Q will show no charge indicator and appear completely dead. To recover, connect the device to a wall charger — not a USB port — and leave it untouched for 20–30 minutes. The charge IC trickle-feeds current below the BMS threshold to bring cell voltage back above 2.8V, at which point the BMS unlocks and normal charging resumes.